Does air dried (5 yr.) hardwood flooring have to go in a kiln?

[Robert Long]

I recently had a call from a customer whom I milled a wack of oak logs for - approximately 5 years ago.

He had it milled into 5/4 boards and has had it stickered all this time outdoors but in a sheltered area, now he is asking if it can be dressed into hardwood flooring......he needs 700sq.ft. of flooring and he wonders if it could be dressed and T&G for flooring and does it need kiln drying.

I don't do flooring but it seems this is a good outlet for me to get into and I may look into a machine or so to shape T&G flooring in the future.

Please help me and him out with these questions!!!!! ???

Robert

[Norm]

My experience has been that air dried material in our area never gets below 10%, and I would suggest that they get it down to 8% to use in a climate controlled house.

Now you can run it into t&g and let it acclimate inside the house for a few weeks stickered to get it down to whatever the average moisture is inside. I really feel that flooring is one thing that you can get away with doing this but the possibility is that you will have some shrinkage during the winter heating season and may get some slight gaps.

[Robert Long]

Thanks Norm

That makes sense and I did suggest he acclimatetise the fooring anyway. I could go out there and get a moisture reading but it's pouring rain and ice right now so what's the point.

Thanks again!

Robert

[RSteiner]

I was reading about how people would dry lumber back in the days when kilns were not around.  White pine was a popular flooring material years ago in many farm houses.  They would let the lumber air dry a couple of years outside in a cover location then bring it into the house when the humidity was at the lowest point.  One book told of letting the wood set in the house at least a year before being fastened down. 

There were still seasonal gaps that occured in the winter months.  My guess is that air dried oak will reach whatever the moisture is in the house with shrinkage and swelling taking place from the point it is nailed down.  I have some red oak that I would like to make into flooring that is air dried so if they go this route keep us posted.

Randy

[beenthere]

Robert
To answer your question, no.  Hardwood flooring does not have to go in a kiln.  However, I'd put it in a kiln, if mine. 

Getting a good reading what the average moisture content is of the air dried lumber will (should) help you decide what to do.

All depends on so many things. Some people don't mind the hardwood flooring strips to shrink causing gaps, that collect dirt and squeak.  I put in oak hardwood flooring that was 6% and kept it wrapped until time to lay it in three bedrooms. I ran short, so used some oak flooring to finish up that had been kiln dried but stored in an unheated shed. That flooring was laid in a hallway, and it showed shrinkage gaps almost within the first couple years. The rest of the flooring is still tight and looks great after 40 years.

[Robert Long]

Thanks people........So far it sounds like it's not a problem as long as he follows some basic rules and conditions.

Robert

[WDH]

If you use the air dried flooring without letting it equilibrate to the "inside relative humidity", you will not be happy.  It will shrink appreciabily.  You can get it there quickly with a kiln.  Without a kiln, you could sticker it inside and check it with a moisture meter until it gets to 7 - 8% like another post said.  It does not have to be "kiln-dried", but it has to be dried to the proper in-use moisture content which is at least 8% or even lower depending on the climate in the region that you live in.  For very hot dry climates, 8% is not low enough.

[Larry]

A lot is dependent on the climate in your area, the type of heating system, whether you air condition or not, type of wood, how it is sawn, flooring width, and finally how big of cracks you want to live with.  Only you can answer these questions.

I did a worse case scenario to just see what would happen.  Southern red oak air dried to 12%.  Made into 8" wide flooring.  Installed in a house that is heated with a wood stove so the wood dries to 6% the first winter.  A crack of .21" between boards is the result.  Not done yet...dust and dirt fills the crack.  No air conditioning in the humid summer so the wood goes back to 10% and expands .14".  Due to dust and dirt in the cracks the whole floor moves and the next winter the crack even gets even bigger when it dries out.

Best case would be narrow strip flooring out of northern red oak that was quarter sawn.  KD to 8%.  Heat pump for heating and cooling.  Installed properly you won't see any cracks at all...ever.

You might want to check with your local flooring guy on his recommendations...those guys install it and get called back 8 to 10 years later to refinish the floors.  They can tell you exactly what is going to happen.

[Robert Long]

WDH and Larry 8) 8)

Thanks for the info, It sounds like you all have the same knowledge and understanding on this and the key is moisture content and relative humidity.

Larry explains an installation that moves with the seasons.........When is a good time to install hardwood flooring then......Winter, spring, summer, fall?

Robert

[WDH]

I know a little bit about wood, but not much about floors.  I will defer to the experts.

[woodbowl]

When the time comes to put the flooring in my house, I thought about bringing it inside, stick it, wrap it in plastic and put a dehumidifier and small fan inside. Hopefully it will bring the moisture down a few more %. Anyone ever heard of this?

[Part_Timer]

Woodbowl

that is how I dried all my lumber before I made the small kiln.  I used to stack and sticker it in the basement.  I made a frame and stapled plastic over it and put a fan and a small DH inside of the frame.  I have a chart that tells how many pints per hour are safe to pull out of a stack.  I could dry stuff down to 7% that way. 

To be honest my kiln is not to much different except it is built into the shop wall with plywood but it works the same way.  I just don't dry green oak in it I have to air dry it first then finish it.

It will work just fine.

[beenthere]

WDH and Larry 8) 8)
........................and the key is moisture content and relative humidity.

.........When is a good time to install hardwood flooring then......Winter, spring, summer, fall?

Robert

When?  all depends on the "key", .......the mc and RH in the room, the mc and RH of the place the flooring has been stored, and the mc and RH of the time period after laying of the floor.

A new home that has just been dry-walled and painted will have high humidity until it drys out. That can have a profound effect on new strip flooring. Having the flooring stored outside in the cold (i.e. high RH) and then bringing it inside where it is warm, dry, and low RH in the winter will have an effect. Having it dry and stored wrapped, then laying it the summer time when the RH is high will also have an effect. So, the jist as I see it, is there is no good answer as to "when?".  I like to have the control that I get when heating the home. Can lower or raise the room temp to get the humidity desired for conditioning the wood.   The wood will move as mc conditions change. Fitting that movement into the plan is a puzzle that just needs to be worked out.

Good luck with the plan.

[Robert Long]

Hey guys...This stuff is great! ;)

Hey beenthere,   I guess I need a name like yours, expierence, expierence, expierence

I will study all the options and try to give the customer the right answer!

Thanks again;

Robert

[woodbowl]

  I have a chart that tells how many pints per hour are safe to pull out of a stack.  I could dry stuff down to 7% that way. 

How many pints per hour are considered safe? How long does it take to pull down to 7%? I would think that the absence of heat would slow things down, but then again if the wood is continuously seeking to equal the moisture content of the air it should travel internally as well, just take longer.  ???

[WDH]

If it is too dry and it swells, that is a big problem if there is not expansion for the floor.  I would calcualte the high and low of M% the floor is likely to see, say 5% to 11%.  Then, make sure there is enough expansion space to handle the wood when it is at say 11% (in the South in the spring when you are running your attic fan), and you should be OK.  It if is down tight without enough expansion space, it will buckle, and that is no fun at all.

[Part_Timer]

Pints per  hour is based on species and how many bf are in the pile.  I have added heat but as the stack dries the DH runs more so you have more heat.  In the summer the DH will keep it 125-130 degrees. If I have a 200bf load of walnut and it is green "just cut and sawed green" it takes around 4 weeks.

Not to overly efficent but I have  $120 in the DH, $30 in the blower, and $20 in plywood. 

[snowman]

I am very far from an expert on this subject but heres my experience. 25 years ago I was building my house at the same time a friend was. We both bough fir and larch T&G 1X4 for flooring. It was kiln dried from local lumber store.He installed his right away and know has lots of gaps. I stickered mine over a winter in my wood heated house and have no gaps whatsoever.

[Robert Long]

Thanks Snowman

I now have enough amo to take to the customer....I am sure your care to details was also in the care of installation and that too affected the results 8)

All the best!!!!!

Robert